1. Field
The present disclosure relates to a transparent liquid crystal display device implemented transparently when an image is not displayed.
2. Related Art
A liquid crystal display device has characteristics such as light weight, a small thickness, low power consumption, and the like, such that application fields for the use thereof have increased. The liquid crystal display device has been widely used in a portable computer such as a notebook computer, an office automation device, an audio/video device, indoor and outdoor advertising display device, and the like. The liquid crystal display device controls an electric field applied to the liquid crystal layer and modulates a light incident from a backlight unit, thereby displaying an image.
The liquid crystal display device has been changed in various forms in accordance with requests of customers. As an example, when the image is not displayed, a transparent liquid crystal display device implemented transparently like glass has been recently developed. The transparent liquid crystal display device is implemented transparently when the image is not displayed, such that the obscured object or landscape locating behind the transparent liquid crystal display device may be seen through the transparent liquid crystal display device. For example, the transparent liquid crystal display device may be implemented in a window. In this case, a user may watch the image through the transparent liquid crystal display device and the outside landscape through the transparent liquid crystal display device implemented transparently in a transparent mode in which does not display the image.
However, the liquid crystal display device includes optical sheets, a light guide plate and a reflection sheet sequentially stacked on a lower portion of a liquid crystal display panel, such that it is difficult to transparently implement the liquid crystal display device. In order to implement the transparent liquid crystal display device, a rear surface of the liquid crystal display panel needs to be designed in a structure which is transmitting light.
FIG. 1 is a perspective view showing a configuration of a transparent liquid crystal display device according to the related art. Referring to FIG. 1, a light source array LA including light sources LS is implemented in edge type backlight unit disposed at a side rather than on a rear surface of a liquid crystal display panel PNL. In addition, the optical sheets and the reflection sheet need to be removed and a cover bottom (not shown) should be implemented so as to enclose edge of the side and rear surface of the backlight unit.
Meanwhile, a light L generated from the light sources LS of the light source array LA moves to a front surface or the rear surface of the light guide plate LGP by the light guide plate LGP as shown in FIG. 2. A portion of the light L moved to the rear surface of the light guide plate LGP is refracted by convex patterns P to move to the front surface, but the remaining light moves toward the outside of the rear surface in the light guide plate LGP. However, since the transparent liquid crystal display device does not include the reflection sheet, the light moving toward the outside of the rear surface in the light guide plate LGP is lost. Therefore, a luminance of the transparent liquid crystal display device is largely lowered. In addition, the convex patterns P of the light guide plate LGP according to the related art are opaquely implemented, such that the convex patterns P are visible by the user in the transparent mode.